The present application claims priority under 35 U.S.C. xc2xa7119 of German Patent Application No. 200 21 553.1, filed Dec. 20, 2000, the disclosure of which is expressly incorporated by reference herein in its entirety.
1. Field of the Invention
The invention relates to a hub for information media in strip or tape form, the hub substantially comprising an outer ring and an inner ring, which generally has three driving grooves for transferring rotational movement of a tensioning shaft to the hub. The width of the winding area of the outer ring corresponds at least to the width of the information medium, and the outer ring and inner ring are connected by radially running webs or ribs.
2. Description of Background Information
The different requirements which the hub has to meet when the tape is being wound up and spooled into cassettes or cartridges, or when carrying out duplicating processes, are taken into account by different hub designs. For example, cores with the greatest possible dimensional stability are required for duplication by the process known as a TMD (Thermo Magnetic Duplication) process. However, owing to high material expenditure and high costs, and also for reasons of weight, a hub of this type should otherwise be avoided as far as possible.
A thermoplastic material, with or without reinforcing materials such as glass fibers or glass beads, is generally used as the material.
In their basic form, all hubs currently on the market comprise an outer ring and an inner ring, the two rings being connected by means of a central web running around radially and attached at the geometrical center of the width of the outer ring, so that a double-T profile is produced. For further stiffening of this profile, it is known additionally to attach ribs extending from the outer ring to the inner ring at certain divisional intervals on both sides of the central web running around radially.
A core of this design satisfies requirements only if the information medium in strip or tape form to be wound onto it has an exactly constant thickness over its width. Due to unavoidable production tolerances in the manufacture of the base film and during coating with magnetic dispersion, an information medium in strip or tape form cannot be manufactured with an exactly constant thickness over its width. This has the consequence that, during the winding operation, the pressure loading of the tape bearing surface of the hub varies over its width. In the worst case, thick points in the information medium in strip or tape form that coincide in their position, lying one on top of the other, cause such high forces on one side of the tape bearing surface during winding onto the hub that the hub twists and the tape bearing surface tilts away to one side and, as a result, a dish-shaped roll is produced. Asymmetrical pressure loading of the hub also occurs if the tape roll on the hub is slightly offset laterally. In the case of dish-shaped tape rolls, the information medium in strip or tape form is stretched on one side, resulting in tape running disturbances in the recording and reproducing equipment and intolerable signal distortions.
On the basis of the aforementioned drawbacks of the prior art, the invention resides in providing a hub of the generic type described above, which does not suffer from the disadvantages of the prior art and, comprises plastic and, for recycling reasons, functions as far as possible without reinforcing additives such as glass fibers or glass beads, in order to avoid a dish-shaped roll when information media in strip or tape form are wound onto the hub.
The hub according to the present invention, may be made of thermoplastic material with or without filler material (e.g. glass fiber). Some examples of suitable material for the hub are polystyrene, ABS (acrylonitrile/butadiene/styrene copolymers), a mixture of polybutylene terephthalate with polycarbonate, PVC (polyvinyl chloride) and polyamide.
According to an aspect of the invention, a hub for an information medium comprises an outer winding area having a width, a central bore and a center point located on the hub, driving grooves on a circumference of the hub, an outer ring, an inner ring, and a connector for connecting the outer ring with the inner ring. The width of the outer winding area of the hub is at least equal to a width of the information medium. The connector comprises diagonal ribs running diagonally at a slant in an axial direction and sloping alternately in accordance with two axial directions of the hub and in neighboring segments. Respective pairs of neighboring diagonal ribs are sloped in different directions and have a further rib between them.
According to another aspect of the invention, the medium comprises a strip or tape form. The width of the outer winding area of the hub may be greater than a width of the information medium.
According to yet another aspect of the invention, a first of the diagonal ribs extends from an end face of the outer ring to an end face of the inner ring. A second of the diagonal ribs extends from an end face of the inner ring to an end face of the outer ring. A further rib may be arranged between the first rib and the second rib.
Moreover, according to the invention, the outer ring and the inner ring are spaced apart by a given distance, and the degree of slant and the degree of sloping of the ribs are selected depending on the width of the outer winding area of the hub and the distance between the outer ring and the inner ring.
The hub may be made of a thermoplastic material with or without filler material, wherein the filler material comprises glass fiber. The hub may be made of one of polystyrene, ABS (acrylonitrile/butadiene/styrene copolymers), a mixture of polybutylene terephthalate with polycarbonate, PVC (polyvinyl chloride), or polyamide.
According to another aspect of the invention, a hub for an information medium comprises one of, strip or tape form, the hub comprising an outer winding area having a width, a central bore and a center point located on the hub, driving grooves on a circumference of the hub, an outer ring, an inner ring and a connector for connecting the outer ring with the inner ring. The width of the outer winding area of the hub is at least equal to a width of the information medium. The connector comprises diagonal ribs running diagonally at a slant in an axial direction and sloping alternately in accordance with two axial directions of the hub and in neighboring segments, wherein respective pairs of neighboring diagonal ribs are sloped in different directions and have a further rib between them. A first of the diagonal ribs extends from an end face of the outer ring to an end face of the inner ring, a second of said diagonal ribs extends from an end face of the inner ring to an end face of the outer ring, and the further rib is arranged between the first rib and the second rib. The outer ring and the inner ring are spaced apart by a given distance, the degree of slant and the degree of sloping of the ribs being selected depending on the width of the outer winding area of the hub and the distance between the outer ring and the inner ring.
A hub according to the invention is more particularly described below. Further details emerge from the description and the drawings.
Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawings.